TextWrangler is a richly-featured and very powerful tool for composing, modifying, and transforming text stored in plain-text files.

At its most basic, a text editor is a tool for simply editing text. You can use a text editor for a wide variety of tasks from cleaning up data, to editing configuration files on your Mac or server, to writing HTML or coding.

Among other things, it can open files from (and save them) to remote FTP and SFTP servers, offers a significantly more powerful grep engine, supports multi-byte and non-Roman text files, can perform Find Differences on pairs of files or folders, and can be invoked from the Unix command line.